As noted in another thread, I decided to change my ageing, rotting alloys and switch to new 18s. I phoned my insurance company a while ago to ask if this had premium repercussions and they said no. Anyway, after I finally decided to splash out, I phoned them back to make sure. This time, they said that they couldn't insure me AT ALL if I put 18s on my car. To be honest, I was amazed at this; this seemed a pretty minor modification to me, especially considering my age (quite advanced ) and good driving record.
So, I had to go through all the hassle of getting quotes from elsewhere, i.e, phoning around, filling in online forms etc, as I really wanted the 18s. I wasn't getting any problems with the 18' alloys thing from other companies.
After getting a good quote, I rang my company to cancel the policy and they said that the info I got before was totally wrong and there was no problem with getting alloys 1 or 2 inches bigger.
So, I suppose the moral of the story is to make totally sure the person you're speaking to knows what they're talking about. I've heard that changing to bigger alloys could be a problem insurance wise, but the info I got for the companies I spoke to suggested that a 1 or 2 inch increase wasn't a problem
I haven't named my company, I've had no problem with them apart from this. In fact, the lady I spoke to today was really helpful and apologetic, so stayed with them!